In a text document, *paste* (not type) the following text:

:---: foo :---:

Execute Tools->Autocorrect->Apply and Edit Changes

Expected:

— foo —

Actual:

:---: foo :---:

(Indeed, there is also a dialog, and the tracking changes; I only show the result of replacement, as suggested by the dialog.)

=====

Now start over, and instead of the previous line, paste

:---: foo bar :---:

and execute Tools->Autocorrect->Apply and Edit Changes

Expected:

— foo bar —

Actual:

:---: foo bar —

In general, an expectation is that the result or autocorrection is the same as if one types the text interactively.

Ref: https://ask.libreoffice.org/t/autocorrect-doesnt-replace-with-m-dash/93097

Code pointer (not an easyhack IMO): SwAutoFormat::SwAutoFormat in sw/source/core/edit/autofmt.cxx